Conversion of PHP function to Javascript

[cinhcet]

you probably can just use the tcp request and send the string the php script is producing as the payload to 172.27.123.50 with port 2001.

If you only ever want to execute your writeQuad("F038 0000", "00000005"); function, then the easiest might be to add a echo $comm3; before the fwrite(...) line and then copy that payload to Node-RED.

EDIT: I just saw that there is the pack function in the php script, so you probably need to send a buffer as the payload and not a string.